hartsoug@oberon.UUCP (Mike Hartsough) (02/12/86)
A while ago, there was a big discussion regarding getting the ETs
into orbit. I would like to address that issue here.
My reference source is "The Space Shuttle Operator's Manual" by
Joels and Kennedy, copyrighted 1982.
At T+0:06:30 the shuttle begins a long shallow dive to prepare for
ET Separation (engines at 100%). Engine power is maintained to keep
the G forces < 3.0.
At: T+0:08:28 Throttle engines down to 65%
T+0:08:38 Main engine cutoff
T+0:08:54 ET Sep
After this, there are two OMS burns for a total of ~2:30 minutes
to establish the shuttle in a standard orbit.
Now...Each SSME produces 375,000# of thrust at 100% throttle, combining
for a total of 1,125,000#.
Each OMS Engine (there are two) produces 6,000# of thrust, for a grand
total of 12,000#.
So! The shuttle goes into a powered dive for 2 minutes at ~1,125,000#
of thrust, then coasts for another 2 minutes before the first OMS
burn, just to get rid of the darn ET! From there, it takes only
2:30 minutes with 12,000# of thrust to reach a standard orbit...
Seems to me as though they're using lots more energy to dump the
thing than to place it into orbit. If that 2 minutes of powered dive
were directed up & out, rather than down & in, there should be no
trouble getting the ET into a non-decaying orbit. Or am I missing
something? <:+)
Each ET weighs in at 78,100# dry (although it may have slimmed down
a little since SSOM was printed). There have been 24 shuttle launches,
meaning that we have thusfar lifted ~937 TONS of aluminum to the very
fringes of space, only to allow it to plummet to destruction.
Well, what do we do with it once we get it there?
Have you ever heard of a Playdoh Fun Factory? Sears (Roebuck & Co)
uses a grown-up version of this to provide a "Custom made aluminum
rain-gutter" for your home. The truck pulls up to your house, they
measure your roof, and then proceed to extrude a seamless aluminum
rain-gutter right on the spot.
I'm sure that Sears would be happy to loan one of their Aluminum
Extruders to Nasa.;^) After a half dozen or so ETs have been saved aloft,
one mission is semi-devoted to converting the ETs into *foamed* Aluminum
I-beams. Nasa simply tells the Space Station Designers that they must
incorporate these I-beams into the construction. Imagine what kind of
a Station could have been built with that 937 tons of ETs which we
callously discarded!
I just recalled an old argument regarding ETs falling out of orbit
a la Skylab...the reason Skylab fell was because we had no way to
get up there and correct the situation (no Apollos, no Shuttle). With
regular missions, we'll be able to keep close tabs on the ETs, and give
em a good nudge every now and then.
Well, this is enough for now...oughta stimulate a lot of discussion.
See ya,
--
Michael J. Hartsough
hartsoug@oberon.UUCP
It is to the interest of the commonwealth of mankind that there should
be someone who is unconquered, someone against whom fortune has no power.
---- Seneca
That's why I'm here.